Rotary peristaltic pumps are usually used for moving liquids through flexible tubing. A typical pump has a rotor assembly with a shaft, two plates, and several rollers. The plates are fixed to the shaft, perpendicular to the axis of the shaft. The rollers are secured, by means of respective axles, between the two plates. The rollers, being nearly identical in diameter, are situated at essentially the same radial distance from and equally spaced angularly about the rotor shaft axis. In turn, the shaft is connected to a motor that applies a rotational force to the shaft. Thus, when power is applied to the motor; the shaft rotates, causing the rollers to describe an orbital path. An occlusion bed has a larger radius than the orbital path of the rollers, and is positioned so that the axis of the occlusion bed surface is coincident with the axis of the rotor assembly. Flexible hollow tubing is positioned between the occlusion bed and the rollers. When the rotor is turned, pressure applied by each roller to the tubing provides a squeezing action between the roller and the occlusion bed, creating increased pressure ahead of the squeezed area and reduced pressure behind that area, thereby forcing a liquid through the tubing.
The spacing between the occlusion bed and the rotor assembly is critical for proper pump operation, and known prior art pumps have a number of disadvantages that limit the ability to provide consistent spacing. For example, the linkage used to open and close the occlusion bed with respect to the pump body is very complicated, requiring numerous components to create the linkage. Moreover, the tolerances of each of the components results in additional complications. However, the spacing between an occlusion bed and a rotor assembly is unforgiving from a tolerance standpoint since it is used both to provide a compressive force between the rotor assembly and occlusion bed pump and to locate the occlusion bed with respect to the rotor assembly.
Further, installation of the tube is complicated in known pumps. For instance, jaws that grip the tube must be manually separated with select tube diameters not automatically fully opened such that the tube can be removed without touching the jaws when the peristaltic pump is opened. Moreover, it is desirable to be able to stretch the installed tube to prolong its useful life. Known peristaltic pumps lack the ability to provide a constant stretching independent of tube size. In addition, pumps are typically preferred that have tube entry and exit on the same side of the pump, to minimize the possibility of interfering with other equipment.
Thus, a pump is desired that provides at least one or more of the following advantages: very accurate positioning of the occlusion bed with respect to the rotor assembly to properly occlude the tubing; retaining automatically a wide range of tubing; is simple to operate; provides consistent tube tensioning independent of the type of tube used; and is installed from a single side or single end of the pump.